On this page
Ozone systems operate in an unusually demanding chemical environment. The same oxidation potential that makes ozone effective for disinfection, contaminant destruction, taste and odor control, and advanced treatment can also challenge materials that were never intended for continuous ozone exposure.
A pipe may look suitable because it handles oxygen. A gasket may work perfectly in ordinary water service. A valve may be rated for the required pressure and temperature. But once concentrated ozone, moisture, elevated temperature, or repeated exposure is added, the material-selection question changes.
This is why materials of construction should be treated as an engineering decision, not a purchasing detail.
Ozone compatibility is not a single yes-or-no material property. The correct selection depends on ozone concentration, dry or wet service, temperature, pressure, water chemistry, exposure time, and the exact material formulation.
At Pinnacle Ozone Solutions, material selection is considered across the complete ozone path, from generator outlet to injection, contact, off-gas handling, instrumentation, and service components. Long-term reliability depends on every wetted and ozone-exposed component being appropriate for its actual duty.
Why Ozone Changes the Materials Conversation
Ozone is a powerful oxidant. When it contacts susceptible materials, it can attack chemical bonds, accelerate aging, embrittle polymers, degrade certain elastomers, and increase the risk of leakage or mechanical failure. The effect is not always immediate. A material can appear satisfactory during startup and then deteriorate after months or years of cyclic exposure.
That makes ozone service different from ordinary compressed gas or water service. Engineers must evaluate not only pressure rating and temperature rating, but also chemical compatibility over the expected operating life.
The most important distinction is often not the material name alone, but the actual service environment surrounding it.
Dry Ozone and Wet Ozone Are Different Services
A component exposed to dry ozone-rich gas leaving the generator is operating in a different environment from a component exposed to humid off-gas or ozonated water. Moisture can materially change corrosion and compatibility behavior.
EPA ozone guidance has historically distinguished between these conditions. Austenitic 300-series stainless steels are identified as ozone-resistant, with 304-series stainless steel used in dry ozone service and 316-series stainless steel recommended for wet ozone service. The same guidance also identifies materials such as PTFE, glass, ceramics, and properly designed concrete as ozone-resistant in appropriate applications.
That distinction is useful, but it should not be interpreted as a universal material-selection rule. Water chemistry, chloride content, temperature, mechanical stress, fabrication quality, and cleaning chemicals can introduce additional corrosion or compatibility concerns. Ozone resistance is one part of the complete materials review.
Metals: Why Stainless Steel Is Common
Stainless steel is widely used in industrial ozone systems because it combines mechanical strength, pressure capability, fabricability, and strong resistance to ozone exposure.
Current Pinnacle generator specifications use 316 stainless steel or 316L stainless steel for major oxygen, ozone, and cooling-water connections on high-output systems such as the Zenith and Apex platforms. That reflects the demanding service expected around industrial ozone equipment.
However, the phrase “stainless steel” is not specific enough for a design specification. Engineers should define the required grade, service, pressure class, joining method, surface condition, and exposure environment.
Materials such as ordinary carbon steel, mild steel, and some copper alloys can present greater oxidation or corrosion concerns in ozone service. Where these materials are proposed, their use should be supported by application-specific compatibility data rather than assumed from normal water-service experience.
Polymers: PTFE, PVDF, and the Importance of Formulation
Polymers are attractive in ozone systems because they can offer excellent chemical resistance, low weight, and practical fabrication. But “plastic” is not a meaningful compatibility category. Different polymers behave very differently when exposed to ozone.
PTFE is one of the most established materials for ozone service and is frequently used in seals, tubing, valve components, and other chemically exposed parts. PVDF is also commonly used in ozone-compatible water and chemical service. Pinnacle technical content identifies 316L stainless steel, PTFE, and PVDF among the materials used in ozone-system construction.
PVC illustrates why generalizations are risky. Historical EPA design guidance notes that unplasticized PVC has been used in some ozone applications, while plasticized PVC can be attacked as ozone reacts with susceptible organic components. Flexible tubing, adhesives, solvent cements, and additives can therefore behave differently from rigid pipe even when both products are described broadly as PVC.
The engineering question should be: What exact resin, formulation, joint method, pressure, temperature, ozone concentration, and exposure condition is being used?
Seals and Gaskets Can Be the Weakest Link
Large piping components receive attention during design, but many field failures begin with much smaller components: O-rings, valve seats, diaphragms, gaskets, flexible connectors, tubing, and sealants.
Elastomer compatibility is especially formulation-dependent. The Parker O-Ring Handbook, for example, identifies EPDM as resistant to ozone, aging, and weathering, while conventional nitrile materials are generally not recommended for ozone or atmospheric aging. Other elastomer families may perform well in some ozone services but behave differently when temperature, water, steam, oils, cleaning chemicals, or compression set are considered.
This is why an engineer should avoid specifying an elastomer family name alone. The actual compound should be rated by the seal or component manufacturer for the complete service environment.
For ozone systems, the question is not simply “Is this gasket EPDM, FKM, silicone, or another material?” It is “Is this specific compound approved for this ozone concentration, temperature, pressure, fluid chemistry, and duty cycle?”
Concentration, Temperature, Pressure, and Time All Matter
Material compatibility is often shown in simplified charts, but an ozone system does not operate as a chart. The severity of exposure changes with the process.
Important variables include:
- Ozone concentration in the gas phase
- Dissolved ozone concentration in the liquid phase
- Dry versus humid or fully wetted service
- Operating and upset temperature
- Gas or liquid pressure
- Continuous versus intermittent exposure
- Water chemistry and other oxidants or cleaning chemicals
- Mechanical stress, vibration, and repeated cycling
A seal that survives intermittent low-concentration ozone exposure may not provide the same life in a continuous high-concentration gas stream. Likewise, a metal that performs well in dry ozone may face a very different corrosion environment when condensation or ozonated water is present.
Material Selection Across the Ozone System
A complete ozone system contains several distinct material environments. Treating all of them as identical can create avoidable reliability problems.
Oxygen Feed and Generator Inlet
This portion of the system is primarily exposed to clean oxygen rather than ozone. Material cleanliness, hydrocarbon control, pressure rating, filtration, and oxygen-service requirements are central considerations.
Generator Ozone Outlet
The ozone outlet sees concentrated ozone-rich gas. Gas piping, valves, seals, analyzers, and fittings must be suitable for that concentration and operating pressure.
Injection and Mass Transfer
Injection components may experience both concentrated ozone gas and water. Venturis, diffusers, static mixers, check valves, side-stream piping, and contact-vessel internals should therefore be evaluated for both chemical environments.
Contact and Ozonated Water Service
Once ozone is dissolved into water, the compatibility review shifts toward wet oxidation service. Tank materials, piping, gaskets, instruments, and downstream components can all be exposed to dissolved ozone and secondary water chemistry.
Off-Gas and Destruct
Off-gas can contain residual ozone and substantial moisture. Condensation can make this one of the more aggressive material environments in the system. Off-gas piping, drains, valves, destruct housings, seals, and sampling components must be selected accordingly.
Compatibility Includes the Components Engineers Do Not See
Material reviews often focus on major piping and equipment, but hidden materials can matter just as much. Adhesives, thread sealants, cable jackets, analyzer tubing, diaphragm materials, pump internals, valve seats, lubricants, coatings, sight glasses, and instrument seals may all be exposed to ozone.
A system can therefore contain high-quality stainless-steel piping and still develop leaks or reliability problems because one small seal, tubing segment, or accessory was not selected for ozone service.
The bill of materials, P&ID, valve schedule, instrument list, and vendor submittals should tell the same story. Ozone compatibility should be traceable through the complete gas and liquid path.
What Material Degradation Can Look Like in the Field
Ozone-related degradation does not always appear as a dramatic failure. Operators and service technicians may first notice small changes such as:
- Cracking or crazing of elastomers and flexible materials
- Hardening, softening, swelling, or loss of elasticity
- Discoloration or surface oxidation
- Repeated gasket or O-ring leakage
- Valve seats that no longer seal consistently
- Tubing that becomes brittle
- Unexpected corrosion near wet ozone or condensate locations
- Persistent ozone odor caused by small gas leaks
These symptoms should not automatically be attributed to ozone alone. Temperature, chemical cleaning, installation damage, UV exposure, pressure cycling, and water chemistry can produce similar effects. The failure mechanism should be investigated before simply replacing the component with the same material.
What Engineers Should Ask During Design Review
Material compatibility becomes much easier to manage when it is addressed during design rather than after startup. Useful questions include:
- Which components are exposed to concentrated ozone gas?
- Which components see wet ozone, condensate, or dissolved ozone?
- What are the maximum ozone concentration, pressure, and temperature?
- Are all valve seats, diaphragms, O-rings, and gaskets explicitly rated for the service?
- Are flexible tubing, sealants, and adhesives included in the compatibility review?
- Does the selected stainless-steel grade match the actual wet or dry environment?
- Have water chemistry and cleaning chemicals been considered separately from ozone compatibility?
- Are replacement parts controlled so an incompatible material cannot be substituted during maintenance?
These questions help convert “ozone-resistant materials” from a general specification statement into a verifiable engineering requirement.
The Pinnacle Engineering Perspective
At Pinnacle Ozone Solutions, ozone equipment is engineered as a complete system rather than as an isolated generator. Material selection is part of that system approach.
Current Pinnacle equipment specifications use stainless-steel process connections on high-output ozone generators, while Pinnacle technical guidance also identifies ozone-compatible materials such as 316L stainless steel, PTFE, and PVDF for appropriate system applications.
The engineering objective is not to create a universal list of acceptable materials. It is to match each component to the actual environment it will experience throughout startup, normal operation, shutdown, cleaning, maintenance, and upset conditions.
That attention to small details matters because a system capable of producing hundreds of pounds of ozone per day can still be limited by a seal, valve seat, tubing connection, or material choice worth only a few dollars.
Conclusion
Ozone-system reliability depends on more than generator efficiency, mass transfer, controls, and process chemistry. It also depends on whether the materials surrounding the ozone can tolerate the environment for years of operation.
Stainless steels, PTFE, PVDF, ozone-rated elastomers, and other compatible materials each have important roles, but none should be selected by name alone. Dry versus wet exposure, concentration, temperature, pressure, water chemistry, formulation, and duty cycle all matter.
For engineers and owners, the best approach is straightforward: define the service conditions first, then verify every exposed material against those conditions.
In an ozone system, the smallest incompatible component can become the largest reliability problem.
Technical Source Notes
- S. EPA, Alternative Disinfectants and Oxidants Guidance Manual. EPA identifies austenitic 300-series stainless steels, glass and ceramics, PTFE, and other materials as ozone-resistant and distinguishes between dry and wet ozone service when discussing stainless-steel selection.
- S. EPA, Technology and Cost Document for the Final Ground Water Rule. EPA notes that ozone in water is corrosive and recommends ozone-resistant pipe materials and inert polymer gasket materials for ozone contact systems.
- Parker O-Ring Handbook, ORD 5700. Parker identifies EPDM as resistant to ozone, aging, and weathering and notes that conventional nitrile materials are not compatible with ozone/weathering; compound-specific service conditions remain important.
- Parker O-Ring & Engineered Seals technical guidance. Parker references ASTM D1171 as a commonly used method for evaluating ozone cracking of rubber compounds.
- Pinnacle Ozone Solutions, Zenith and Apex technical specifications. Current high-output generator specifications identify 316 stainless steel and 316L stainless steel for major process and cooling-water connections.
- Pinnacle Ozone Solutions technical articles on water reuse and engineered ozone systems identify 316L stainless steel, PTFE, PVDF, and ozone-rated sealing materials as common materials used in ozone-system construction.
